In a gear motor, a gearbox is assembled with a motor, and the output speed and output torque of the motor are changed by a speed change gear mechanism to accommodate a load. For example, an open-close mechanism for a rear door of a vehicle utilizes a planetary gear motor to reduce the rotation speed and increase the torque of the motor to successfully open or close the rear door.
Currently, the speed change gearbox is usually mounted to the motor through a mounting plate. The mounting plate is mounted on an outer housing of the motor, and various components of the speed change gearbox are then mounted to the mounting plate through a mounting structure in the form of a hole-pin engagement. However, the engagement holes in the existing designs have the same size, which can easily cause the following issues: if engagement holes are not coaxially arranged and are slightly misaligned, the pin cannot be easily inserted into the holes during assembly, which may also cause the pin to deform; in addition, due to the misalignment, the pin can easily fall off the hole during use of the gear motor.